[kernel] Add channel objects

Add the channel object for sending messages between threads. Currently
no good of passing channels to other threads, but global variables in a
single process work. Currently channels are slow and do double copies,
need to refine more.

Tags: ipc

src/drivers/nulldrv/main.cpp

@@ -5,6 +5,10 @@
 #include "j6/errors.h"
 #include "j6/signals.h"
 
+const char message[] = "Hello! This is a message being sent over a channel!";
+char inbuf[1024];
+j6_handle_t chan = j6_handle_invalid;
+
 extern "C" {
 	j6_status_t system_log(const char *msg);
 
@@ -17,6 +21,11 @@ extern "C" {
 	j6_status_t thread_sleep(uint64_t til);
 	j6_status_t thread_exit(int64_t status);
 
+	j6_status_t channel_create(j6_handle_t *handle);
+	j6_status_t channel_close(j6_handle_t handle);
+	j6_status_t channel_send(j6_handle_t handle, size_t len, void *data);
+	j6_status_t channel_receive(j6_handle_t handle, size_t *len, void *data);
+
 	int main(int, const char **);
 }
 
@@ -24,6 +33,13 @@ void
 thread_proc()
 {
 	system_log("sub thread starting");
+
+	j6_status_t result = channel_send(chan, sizeof(message), (void*)message);
+	if (result != j6_status_ok)
+		thread_exit(result);
+
+	system_log("sub thread sent on channel");
+
 	for (int i = 1; i < 5; ++i)
 		thread_sleep(i*10);
 
@@ -34,21 +50,49 @@ thread_proc()
 int
 main(int argc, const char **argv)
 {
-	j6_handle_t child = 0;
+	j6_handle_t child = j6_handle_invalid;
 	j6_signal_t out = 0;
 
 	system_log("main thread starting");
 
-	j6_status_t result = thread_create(&thread_proc, &child);
+	j6_status_t result = channel_create(&chan);
 	if (result != j6_status_ok)
 		return result;
 
+	system_log("main thread created channel");
+
+	result = thread_create(&thread_proc, &child);
+	if (result != j6_status_ok)
+		return result;
+
+	result = object_wait(chan, j6_signal_channel_can_recv, &out);
+	if (result != j6_status_ok)
+		return result;
+
+	size_t len = sizeof(inbuf);
+	result = channel_receive(chan, &len, (void*)inbuf);
+	if (result != j6_status_ok)
+		return result;
+
+	for (int i = 0; i < sizeof(message); ++i) {
+		if (inbuf[i] != message[i])
+			return 127;
+	}
+
+	system_log("main thread received on channel");
+
 	system_log("main thread waiting on child");
 
 	result = object_wait(child, -1ull, &out);
 	if (result != j6_status_ok)
 		return result;
 
+	result = channel_close(chan);
+	if (result != j6_status_ok)
+		return result;
+
+	system_log("main thread closed channel");
+
 	system_log("main thread done, exiting");
 	return 0;
 }

src/drivers/nulldrv/main.s

@@ -30,6 +30,10 @@ SYSCALL thread_create, 0x19
 SYSCALL thread_exit, 0x1a
 SYSCALL thread_pause, 0x1b
 SYSCALL thread_sleep, 0x1c
+SYSCALL channel_create, 0x20
+SYSCALL channel_close, 0x21
+SYSCALL channel_send, 0x22
+SYSCALL channel_receive, 0x23
 
 global _start
 _start: